Hibernation: Check if ACPI is enabled during restore in the right place

The following scenario leads to total confusion of the platform firmware on
some boxes (eg. HPC nx6325):
* Hibernate with ACPI enabled
* Resume passing "acpi=off" to the boot kernel

To prevent this from happening it's necessary to check if ACPI is enabled (and
enable it if that's not the case) _right_ _after_ control has been transfered
from the boot kernel to the image kernel, before device_power_up() is called
(ie.  with interrupts disabled).   Enabling ACPI after calling
device_power_up() turns out to be insufficient.

For this reason, introduce new hibernation callback ->leave() that will be
executed before device_power_up() by the restored image kernel.   To make it
work, it also is necessary to move swsusp_suspend() from swsusp.c to disk.c
(it's name is changed to "create_image", which is more up to the point).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/acpi/sleep/main.c b/drivers/acpi/sleep/main.c
index acfb01b8ec8..048295ec370 100644
--- a/drivers/acpi/sleep/main.c
+++ b/drivers/acpi/sleep/main.c
@@ -257,6 +257,15 @@ static int acpi_hibernation_enter(void)
 	return ACPI_SUCCESS(status) ? 0 : -EFAULT;
 }
 
+static void acpi_hibernation_leave(void)
+{
+	/*
+	 * If ACPI is not enabled by the BIOS and the boot kernel, we need to
+	 * enable it here.
+	 */
+	acpi_enable();
+}
+
 static void acpi_hibernation_finish(void)
 {
 	acpi_leave_sleep_state(ACPI_STATE_S4);
@@ -288,6 +297,7 @@ static struct platform_hibernation_ops acpi_hibernation_ops = {
 	.finish = acpi_hibernation_finish,
 	.prepare = acpi_hibernation_prepare,
 	.enter = acpi_hibernation_enter,
+	.leave = acpi_hibernation_leave,
 	.pre_restore = acpi_hibernation_pre_restore,
 	.restore_cleanup = acpi_hibernation_restore_cleanup,
 };